1. Field of the Invention
The present invention relates to the use of single-dielectric barrier discharge plasma actuators for drag reduction on wings, nacelles and/or fuselage of aerodynamic vehicles designed for vertical take-off and landing (VTOL).
2. Description of the Related Art
Aircraft may include surfaces that have regions where the airflow over the surface is not able to follow the contour of the surface. The airflow is said to “separate” from the surface in these regions. The separation of the airflow from the surface may result in increased fuel consumption, reductions and/or limitations on travel speed and/or range, and the carrying capacity of the aircraft. For example, in airplanes that take-off vertically like a helicopter and then change configuration to fly as a normal airplane, i.e. tilt-rotor airplanes, the separation of the airflow from the rotor on the wing during take-off results in resistance to the upward motion of the wing, also known as download, and to a reduction of the carrying capacity and operational range of the tilt-rotor airplane.
Previous attempts to prevent airflow separation included blowing and/or suctioning air from orifices in the surface located in or near the separated flow region. Slots were formed in the surface and jets of pulsating air were periodically discharged from the slots to prevent airflow separation. The jets were formed by voice coil based actuators or piezoelectric actuators provided in a linear array along the surface.
The use of voice coil based actuators or piezoelectric actuators to prevent airflow separation required a change in the design of the surface to accommodate the actuators. The voice coil based actuators or piezoelectric actuators added weight and expense to the aircraft from the slot, actuators and wires. It was also difficult to retrofit the voice coil based actuators or piezoelectric actuators to existing aircraft. Use of such actuators on rotor blades required that they fit within the contour of the airfoil. To generate pulsating jets of air required a vibrating membrane of some construction which results in airframe noise and vibration in addition to the volume requirement inside the lifting elements.